The proposed research continues to investigate the effects of anesthesia on metabolism, circulation and respiration in normal and abnormal states. Specifically we will investigate the mechanism of malignant hyperthermia using an isolated hind limb preparation so as to study the responses of a large mass of muscle. The protocol can then duplicate the events that lead to triggering in awake swine. This preparation will also help to evaluate the results from study of muscle biopsies in organ baths, since the results are sometimes equivocal. Further studies on relaxant-induced hyperkalemia will be to determine the duration of susceptibility (and probably supersensitivity) in rats with upper motor neuron lesions. At the present time the duration of risk in humans with upper motor neuron lesions is unknown, but is probably greater than one year.